Can a married woman date platonically?

My wife and I met back in college. We were very close and serious with each other almost immediately. One thing she always did was take other men out on occasional "dates." These were platonic and usually involved guys from her high school (not exes) or men from back east her mother wanted her to take out when they were in town. She started doing this in high school. She always let me know when she was doing this and I was fine with it. Usually just dinner and a movie or something similar. She was never a drinker. This has continued, though more rarely, since we married. There has never been a problem and I trust her completely. Most recently it was a younger Danish colleague of her father who came to do research at the university for a few days in town. She took him to see a movie and then to coffee and he was very happy and appreciative. My friends say I am crazy and one college buddy says he thought I was then too (one said no big deal). Are they right? Can a woman go out with another man for the night without trouble? Is this okay?